Known vehicle heat-exchange modules include one in which a condenser for an air-conditioning device and/or a radiator for cooling an engine, a propeller fan, a fan motor, and so forth are arranged in the front part of an engine compartment in this order from the front side and are integrated into a module (also referred to as a CRFM). This CRFM is configured by providing a shroud having a flow channel, whose cross-sectional area is gradually reduced towards the propeller fan facing the downstream side of the condenser and/or the radiator, such that the cooling air (outside air) sucked-in through the condenser and/or the radiator is guided to the propeller fan.
In such a CRFM, one or two propeller fans are provided depending on the amount of heat exchanged at the condenser and the radiator. In general, for a condenser and a radiator having a horizontally oriented rectangular shape, a single-fan configuration provided with one propeller fan is employed if the airflow rate, for a fan motor voltage of 12 V, is approximately 2,000 m3/h or less, and a double-fan configuration provided with two propeller fans is employed if the airflow rate is 2,000 m3/h or more. In addition, if the airflow rate is about 2,000 m3/h, the fan motor input power is approximately 240 W or less.
In the case of the double-fan configuration, because the wind speed distribution of the cooling air flowing through the heat exchangers (the condenser and the radiator) is made uniform in comparison with the single-fan configuration, the pressure drop at the heat exchanger is not increased, the motor input power is not increased, and the input power per fan motor is reduced; therefore, there are some advantages, such as the ability to make the fan motor compact and lightweight, which facilitates the procurement thereof, and so forth. However, because two propeller fans and fan motors are required, the number of parts is increased, and although the respective weights of the fans are reduced, the total weight is increased. Furthermore, because the fan motor accounts for a large proportion of the cost of the fan unit, although the cost per motor is reduced, the total cost, including the cost of the two motors, becomes high.
On the other hand, various problems such as an increase in the motor input power, upgrading of the fan motor associated therewith, an increase in noise, and so forth are caused if the single-fan configuration is employed instead of the double-fan configuration, which should normally be employed, because a deviation is caused in the wind speed distribution of the air flowing through the heat exchanger, and the pressure drop (ventilation resistance) due to the heat exchanger is increased. In addition, PTLs 1 and 2 show configurations in which a drop in fan efficiency is suppressed by making a motor support beam have a stator-blade shape. In addition, PTL 3 shows a configuration in which an opening is provided at the periphery of the bell-mouth of the shroud in order to suppress a drop in cooling performance while driving due to the reduction in a ventilation area of the shroud. Furthermore, PTLs 4 to 6 show multi-blade configurations in which the number of blades is increased in order to make the depth dimension (axial dimension) of a propeller fan smaller.
In addition, PTLs 5 and 6 show configurations in which winglets are provided on the suction surface and the pressure surface in the vicinity of the outer periphery and the root part of the blade, respectively, thereby rectifying the airflow and suppressing separation, stalling, and so forth at the blade surface to achieve an improvement in fan efficiency. Furthermore, PTL 7 shows a configuration in which noise is reduced by lowering the rotational speed and making the flow distribution of cooling air uniform in the circumferential direction by forming a bell-mouth at the maximum size that permits the whole perimeter thereof to be secured within the shroud and making the propeller fan have as large a diameter as possible.